Drag and Drop from Grid to Tree and backwards

Hi there!

Since a few days now I try to change Saki's 'Grid to Tree Drag and Drop' to work in both directions. But all I get is an 'almost' working application. I am stuck
Now it works as far as I can drag an item from grid to tree, within tree, within grid but if i drag it from tree to grid, it doesn't drop. It just shows the green hook.
I also tried to differ the ddGroup from tree and grid, but then nothing works anymore.
This is too much for an ExtJs beginner. Can anyone of the good guys help me? PLEASE